In the time of the second-generation (2G) mobile communication, development of data service is limited because network bandwidth and the intrinsic disadvantages of Short Message Service (SMS) are difficult to overcome. As the development of the third-generation (3G) mobile communication system, various data services based on it have been developing rapidly and have a wider field than that based on the 2G mobile communication system.
Multimedia technology makes it possible for people to represent and transmit messages more accurately and emotionally. The 3G mobile communication system introduces multimedia technology into the mobile communication field. A new message service, Multimedia Message Service (MMS), will change the short message communication modes fundamentally. The MMS provides a non-real-time multimedia communication mode, and a user can send or receive a multimedia message consisting of texts, images, videos and audios. Based on this platform, richer services can be derived and better service quality can be provided.
An MMSC is responsible to send messages consisting of pure texts, pictures, videos, audios and other media over a network. The MMSC can provide three basic service capabilities: a point-to-point service capability, a point to application service capacity and an application to point service capacity, and also two extended service capacities: a point to multipoint service capacity and an application to multipoint service capacity.
MMSC is located on IP network, and connected to a wireless network through a Wireless Application Protocol (WAP) gateway. Implementation of MMSC is independent on the specific wireless networks. MMSC can support multiple networks such as GSM, GPRS, WCDMA, CDMA, CDMA2000 and the 3G networks in future.
The system structure of an MMSC is illustrated in FIG. 1, and the related system interfaces are determined by each network element. The definition and description of interfaces are concentrated on the standard procedure of service access. At the same time, a lowest requirement for the specification of the system physical interfaces is defined to ensure the variety of the system.
FIG. 1 illustrates the system structure of MMSC according to the prior art. The MMS terminal shown in FIG. 1 provides multimedia message services through an MMS user agent. The MMS user agent, which provides functions for user to browse, edit and process a multimedia message and operations for user to send, receive and delete a message, is an application in an MMS terminal, and is connected to the MMS relay/server which is also called MMSC through the reference point MM1. An MMSC makes protocol transforming, content adapting, storing and dispatching for multimedia messages, performs multimedia message transferring between different multimedia devices, and also produces a Charging Detail Record (CDR) for charging. An MMS user database which stores user information, personalized information and interface information etc. is connected to the MMSC through the reference point MM6. In a target network, the MMS user database is a part of MISC system and is integrated in the MMSC at present. An MMS value added service application for providing value added services is connected to the MMSC through the reference point MM7. A billing system for performing the charging operation of MMSC is connected to the MMSC through the reference point MM8. Peripheral devices, such as an email server, a Short Message Service Center (SMSC) and a facsimile etc, are connected to the MMSC through the reference point MM3 and provide external services.
As shown in FIG. 2, the reference point MM4 is an interface of different MMSCs and is used for transferring messages between different MMSCs through the Simple Mail Transfer Protocol (SMTP). The message transferring protocols needing to be satisfied when transferring multimedia messages over interface MM4 are mainly the protocols of the Third Generation Partnership Project (3GPP).
FIG. 3 is a message transaction flowchart of the MM4 interface. As shown in FIG. 3, forwarding multimedia messages between different MMSCs comprises the steps as follows.
a. After an originator MMSC has received the multimedia message (MM) submitted by an originator terminal and has successfully discovered a certain peer MMSC, the originator MMSC should forward the multimedia message to the recipient MMSC using the routing forward request message MM4_forward.REQ including control information of MMS and content of the MM. Correspondingly, the recipient MMSC should respond with a routing forward response message MM4_forward.RES including the status requested in the MM4_forward.RES. The definitions of the two messages concerning about this step are shown in Table 1.
TABLE 1Name of abstractMessagemessagetypeDirectionMM4_forward.REQRequestOriginator MMSC−> recipientMMSCMM4_forward.RESResponseRecipient MMSC−>originatorMMSC
b. After the recipient MMSC has delivered the MM, if the recipient terminal does not allow generating a delivery report, the recipient MMSC will not generate a delivery report; in the contrary, if the recipient terminal allows generating a delivery report, a delivery report MM4_delivery_report.REQ will be generated and sent to the originator MMSC. The delivery report only contains control information of MMS. The format of MM4_delivery_report.REQ specified in 3GPP is defined as shown in Table 2.
TABLE 2Information elementPresenceDescription3GPP MMS VersionMandatoryThe MMS version of the originator MMSRelay/Server as defined by the present document.Message TypeMandatoryThe type of message used on reference point MM4:“MM4_delivery_report.REQ”.Transaction IDMandatoryThe identification of the MM4_delivery_report.REQ/MM4_delivery_report.RES pair.Message IDMandatoryThe identification of the original MM.Recipient addressMandatoryThe address of the MM recipient of the original MM.Originator addressMandatoryThe address of MM originator of the original MM.Date and timeMandatoryThe time and date when the MM was handled, i.e.searched, time overridden and rejected.AcknowledgementOptionalA request for MM4_delivery_report.RESRequestMM stateMandatoryThe state of MM, such as the MM has been searched,time overridden and rejected.MM state textOptionalThe corresponding text of MM state.
c. If having received a delivery report from the recipient MMSC, the originator MMSC responds a delivery report response message MM4_delivery_report.RES providing status information of the condition requested by the MM4_delivery-report.REQ. It is necessary for MMSC to support the MM4_delivery-report.REQ. The definitions of two messages of delivery report are shown in Table 3.
TABLE 3Name of abstract MessageTypeDirectionMM4_delivery_report.REQRequestRecipient MMSC −>originator MMSCMM4_delivery_report.RESResponseOriginator MMSC −>recipient MMSC
In the above sending flow of the MM4 interface message, the MM4_forward.REQ, MM4_forward.RES, MM4_delivery_report.REQ and MM4_delivery_report.RES are protocol messages of MM4 interface, the other messages are for other reference points, which can be supplement of the above flow.
With the above-mentioned steps and the prior message transmission protocol structure, forwarding MMs between different MMSCs can be implemented.
Nevertheless, though the function of forwarding MMs between different MMSCs in the message sending process can be realized with the prior message transmission protocol structure, if the following situation happens, the corresponding functions cannot be realized with the prior message transmission protocol structure.
When an MM is being forwarded between different MMSCs, according to the 3GPP protocols, if the recipient terminal does not allow generating a delivery report, the recipient terminal shall not send a delivery report to the originator terminal even the originator terminal required so. According to the prior MM forwarding process, in this case the recipient terminal does not generate a delivery report, the originator MMSC can only depend on the MM4_forward.RES to determine whether the MM forwarding is successful, and cannot know exactly whether or not the MM is delivered correctly to the recipient terminal from the originator terminal.